The present invention relates in general to coke oven processes and in particular to a new and useful method of removing hydrogen sulfide from crude coke oven gas.
The coke oven gas produced during the carbonization of coal must be subjected to various purifying treatments before using it for underfiring, for a city gas system, or for other purposes. More particularly, it is usual to desulfurize the coke oven gas in a low pressure process, to prevent corrosion and protect the environment. Such scrubbing processes with all their advantages and disadvantages are described and shown in Ullmann's Encyclopedia of Chemical Technology, Volume 10, Third Edition, March 1958, Pages 307 to 322. According to this digest, of the entire amount of coke oven gas produced in a coking plant, 95% is usually desulfurized in a so-called wet process under normal pressure, and only the remaining percentages, which is not needed in the plant itself for underfiring, for example, is further desulfurized to a quality high enough for city gas. This is done under pressure in various "wet processes", while employing liquid scrubbing agents, or in dry processes, such as with the use of bog iron ore or residuals from bauxite working processes (see Ullmann's Encyclopedia, Vol. 10, pages 307, 308 and 314).
Different methods with different scrubbing agents are employed for the preliminary cleaning under normal pressure, and the subsequent cleaning under higher pressure. Considerable costs must thus be incurred to treat and regenerate the different scrubbing agents in cycling processes which are needed for reasons of economy. With a subsequent dry cleaning with bog iron ore and similar substances suitable for absorption, it is increasingly difficult to procure them in amounts sufficient for the huge gas column to be treated. In addition, the methods of regenerating such sulfur-enriched substances and of recovering sulfur in such regeneration plants are uneconomical.